1831 Bust Half Dollar - Die Bulge?

SpectrumLuster

Have an 1831 Half Dollar with an obvious bulging in the left obverse field. I've only seen two examples of the very rare Overton-120 R-6 which can run +$5,000 for a 'Fine' grade but can't find the characteristics that make it such a rare piece. Do I have a rare type, here?

LVGT

Go to coinzip

jayPem

Without a reverse photo....I'll take a wild guess it's o-103 and the "bulge" is lapped die clashing. Very wild guess though.

SpectrumLuster

Any more opinions?